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Simone Lan Li, Richard W Hertle; Routine Testing of Visual Evoked Potential Asymmetry in Pediatric Patients with Albinism. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4891.
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© ARVO (1962-2015); The Authors (2016-present)
Visual evoked potential (VEP) asymmetry in which a preponderance of nasal and temporal retina afferents project to the contralateral hemisphere after full-field monocular stimulation is considered to be specific to albinism. In this study, we examined whether a commercially available VEP testing unit, under ordinary clinical conditions, could evaluate VEP asymmetry in pediatric patients with albinism.
Monocular transient pattern onset/offset VEP testing was performed using a UTAS Visual Diagnostic Test System manufactured by LKC Technologies Inc.® (MD, USA). The stimuli were presented on a 19-inch Acer LCD monitor. Three scalp electrodes were positioned with reference to bony landmarks and in proportion to the size of the head, according to the International 10/20 system. The center electrode was placed at Oz and the lateral electrodes placed at O1 and O2 (about 3 cm away on both sides of Oz). Only VEP results obtained from the lateral electrodes were analyzed.
Between January 2016 and November 2016, 16 albino children of various types from OCA 1-4 (63% male; age range: 0.25-14.2 yo, with mean age of 5.07 yo) were recruited. The VEP results in 11 children (69%) were irreproducible in both right (OD) and left (OS) eyes recorded at both O1 and O2. In the remaining 5 children (31%), reproducible VEP results were found in only one eye at one of the lateral electrodes, or in only one eye at both lateral electrodes, making determination of laterality impossible in this cohort.
VEP asymmetry can only be determined using reproducible recordings in both eyes. Our current routine clinical VEP testing using a pattern onset/offset with the commercially available LKC UTAS Visual Diagnostic Test System paired with an LCD monitor is insufficient to determine asymmetry in a mixed clinical population of patients with albinism. This could be due to the difficulty for LCD displays to maintain the mean luminance during the transition from checkerboard pattern to diffuse blank screen in a pattern onset/offset presentation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
VEP tracing showing our definition of irreproducible data OD and OS
VEP tracing showing our definition of irreproducible data OD and reproducible data OS
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